This article describes how to configure VLAN trunking on the NetScaler VPX instance running on XenServer 5.5.

Background

The NetScaler VPX older than 9.3 does not support 802.1q tagged VLANs. If you try to bind a VLAN to an interface with the -tagged option, you receive the message "ERROR: Operation not permitted".

However, you can create tagged VLANs between a network switch and the XenServer host, and each tagged VLAN can be connected to the NetScaler VPX instance as a virtual interface. The following diagram illustrates this concept:

Requirements

• XenServer 5.5
• A compatible version of XenCenter
• NetScaler VPX instance

Instructions

To configure VLAN trunking on the NetScaler VPX instance running on XenServer 5.5, complete the following procedure:

1. Configure the network switch for 802.1q trunking. Refer to the configuration documentation for your switch. In this example, the switch is a Cisco running IOS 12.2, and the relevant configurations are as follows:
   interface GigabitEthernet9/1
   description interface to the XenServer NIC 1
   switchport
   switchport trunk encapsulation dot1q
   switchport trunk allowed vlan 20
   switchport mode trunk
   end
   This configuration specifies that the interface GigabitEthernet9/1 is an 802.1q trunk port, the native VLAN is VLAN1 (the default), and that VLAN 20 is allowed across the trunk to the XenServer.

2. Add the VLAN to the XenServer configuration:

   1. Open XenCenter and add a network in the XenServer.

      

   2. Select the External Network option, and then click Next.

      

   3. Type the name for a Network and an optional description, and click Next.

      

   4. Select the physical interface, enter the 801.2Q VLAN ID, and click Finish.

      

      You can see the new network in the XenServer configuration.
3. Connect the VLAN to the NetScaler VPX instance:
   1. From the NetScaler VPX instance, select the Network tab and click Add Interface.

      

   2. Select the network (VLAN) and click Finish.

      

      Note the Device number in the NetScaler VPX Network configuration.

      

4. Configure the NetScaler VPX:
   1. Restart the NetScaler VPX instance. After it restarts, log on and run the show interface command. Find the device number, it will be the same as the Device number from the previous step. This is the virtual interface where the VLAN terminates on the NetScaler VPX.

      

      This can also be found in the Graphical User Interface (GUI) of the NetScaler VPX Network > Interfaces.

      

   2. Create a VLAN and bind it to the virtual interface. For example, in the NetScaler CLI:
      add vlan 20
      bind vlan 20 –ifnum 1/3 –ipaddress 172.16.20.1 255.255.255.0

      

      This can be done in the NetScaler GUI under Network > VLANs > Add.

• While adding the VLAN and binding it to an interface, a typical configuration would also include binding an IP address. Refer to the NetScaler VPX documentation for information regarding IP addresses.      

• Note that because of the VLAN tagging is actually being done at the XenServer, and the 802.1q tags are not actually being passed to the NetScaler VPX instance, the VLAN number configured within the NetScaler VPX instance does not need to match the VLAN ID of the VLAN on the trunk between the switch and the XenServer (VLAN ID 20, in this example). However, it is recommended to match the VLAN IDs for consistency and manageability.

• Starting with NetScaler VPX 9.3 and later, NetScaler VPX instance allows tagging.